By Kimi Eisele for the Sherwin Williams, Industry Partner of ASID, Magazine, STIR

Gail Mayhugh believes paint color is alive. “It will change from morning to noon to night because of light coming through windows or lights being turned on,” says the Las Vegas interior designer, referring to the phenomenon that scientists refer to as color inconstancy.

Color perception is the result of a complex interaction between the light reflected off a surface and the chemical properties of its color source. Technically, this is called the spectral reflectance curve. Metamerism occurs when colors respond differently to light because of the way they were formulated; their spectral curves are different.

“If you take a look around a room, all the objects you see – fabrics, ceramics, paint – have different types of colorants, dyes, and pigments, each with differing properties,” says Roy S. Berns, professor of color science, appearance, and technology at Rochester Institute of Technology in New York.

Unlike the way we hear sounds, which we sense at individual frequencies, we see color by transforming many wavelengths into just a few signals, Berns says. ” As a consequence, many combinations can result in the same color.”

Different light sources can result in different effects, says Thomas A. Hough, color science specialist with Whiterock Design in Tuscon, Arizona. “Light from a tungsten light bulb has more yellow content, while light from a fluorescent lamp has more blue content,” Colors that appear the same under one type of lighting can respond differently under another.

Color inconstancy tends to occur more often with complex color hues, says Morton, also the author of Color Voodoo, a series of publications about color. “Purple, brown, puce, mauve, sage green, celadon green – those are the colors that are more likely to ‘shift.'”

Paint finishes can also affect color appearance. Because shinier surfaces reflect light in a single direction while flat surfaces reflect light in all directions, colors can appear different in matte versus gloss finishes, Berns says.

“To minimize problems associated with metamerism, it’s best to use the same paint manufacturer throughout a project whenever possible,” says Sheri Thompson, director of Sherwin-Williams’ Color Marketing and Design. Different manufacturers use different formulas of pigments or colorants to arrive at a specific hue. The fewer the pigments, the less likely the finish will be affected by changes in lighting.

It’s also essential to view colors under the conditions in which they’ll be used. Many leading paint manufacturers provide special light booths that allow consumers to view paint samples under a variety of lighting sources. But that accounts only for indoor lighting. Outdoor light also can affect the way a color appears.

Both Morton and Mayhugh recommend testing paint color in the location where it will be used by buying small samples of color and painting poster boards, which can be moved easily from room to room for easy comparison with other design elements. “That’s the key,” Morton says.